Petroleum refining and petrochemical processes frequently involve heating process streams in a furnace. The interior chamber of the furnace contains tubes which contain process streams. The interior chamber is heated by a plurality of burners which receive a fuel which combusts to produce heat.
Some burners are “raw gas” or “nozzle mix” burners. In this design, fuel and combustion air do not mix until the fuel and combustion air enter a primary combustion zone downstream from the fuel nozzle, perhaps inside an interior chamber of the furnace. While the flames associated with such burners are well-defined, the flames have a tendency to produce high levels of nitrous oxide (NOx) emissions, which is undesirable, and in some cases, exceed government emissions regulations.
In order to minimize the formation of combustion-generated NOx emissions, staged fuel burners have been used in refinery and petro-chemical plant heaters. Numerous modifications have been made to the design of staged fuel burners in attempts to improve the reduction of the NOx emissions generated during combustion.
Low-NOx emissions fuel burners are staged to provide the minimum possible combustion generated NOx emissions levels. To accomplish “staging” the staged fuel burners have multiple fuel gas tips (typically eight or more) and multiple fuel manifolds. These gas tips have very small discharge ports and are located in the vicinity of combustion zones that contain combustion products that have a very high temperature. As a result, the tips can overheat. The overheating, coupled with occasional debris in the fuel, can lead to significant plugging of the discharge ports. The susceptibility to plugging reduces performance and increases the maintenance required for cleaning, each of which impacts the output and production levels of a refinery or processing plant.
Since they have multiple tips, these types of burners can be expensive. Additionally, the complicated tips require a significant amount of installation time. Beyond the initial installation, replacing damaged burners can be problematic because the downtime can negatively impact the output and production levels of a refinery or processing plant.
Therefore, it would be desirable to have a burner that addresses one or more of these problems.